Two cases were found:
1) Filtering on location using uppercase (as they are found in the activity) returns onthing (i.e. an empty list). Changing to lowercase works, even though in reality e.g. 'DE' != 'de'
2) Filtering on locations with dashes (as they are found in the activities) returns nothing (i.e. an empty list). Changing to lowercase in this case doesn't change anything, e.g. 'ca-qc', CA-QC', 'caqc', CAQC' all return nothing.